Apparatus for coking coal



Aug. 30, 1932. s. w. PARR ET AL 1,374,344

APPARATUS FOR COKING COAL Original Filed Jan. 29, 1935 2 Sheets- Sheet lINVENTORS 1932- s. w.- PARR ET AL APPARATUS FOR COKING' COAL 2Sheets-Sheet 2 Original Filed Jan. 29, 1925 K/INVENTOBS.

BY Z 7. f3 ATTORNEY Patented Au 30, 1932 1,874,344

UNITED STATES PATENT OFFICE SAMUEL W. PARK AND THOMAS ERNEST LAYNG, OFURBANA, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO URBANA COKECORPORATION, 01' URBA NA, ILLINOIS, A CORPORATION OF DELAWARE APPARATUSFOR COKING COAL Original application flied January 29, 1925, Serial No.5,499. Divided and this application flied July 30,

1925. Serial No. 46,935.

Our invention relates to a process of treatly designated as non-c okingcoal. Our ining coal for the purpose of educing hydroventlon makes 1tpossible to produce from carbons therefrom and converting the fueleither cokmgcoals or-so-called non-coking into coke; and our inventionalso relates to coals a coke articularly ada ted for domesan apparatuswhereby our improved process tic use or, if eslred, a cokesuitablefonmetal- 5 can be carried out. lurglcal purposes, while at thesame time se- The present application is a divisional apcuring asbyroducts, oils, tars or the like, plication based on our applicationSer1alNo. r1ch 1n valua le constituents and less con- 5,499, filedJanuary 29, 1925. tammated with deleterious substances than is Accordingto present practice, coal is coked he case Wlth ordinary by-productpractices. 55

i h i b hi Ovens or i th more -In general our process consists ofheating modern by-product ovens. In the former fuel such as coaluniformly throughout up to t th ,1 i 5 e d on a h th and close to thetemperature at which hydrocarignited with insu cient supply of air and11 11 vapors begin to form and then confin ng 15 the volatileconstituents of the fuel are all he f el In a Closed ontamcr andsupplylng 60 either consumed or wasted. In the ordinary it withsufficient heat to complete the coking by-product process, the coal ischarged into operation. The preliminary heating up to externally heatedcoking chambers and the the cr tical temperature 1s bestperiormed bygases and vapors are led away for recovery agltatlng the fuel whilesupplying heat thereof the valuable constituents. In both of to. Weprefer to carry out the process in this 65 these processes the coal issubmitted to temmanner so as to avoid the formation in the peratures andto conditions which are not body of fuel of zones of differenttemperature conducive to economical production of the in Which the fuelis in various stages of dedesired products, and in the-case of thebycomposition, part ofit being converted preproduct processes thevapors'are exposed to maturely into coke. Where fuel is placed in 7temperatures and conditions which seriously the ordinary by-productretort and slowly reduce the proportions of some of the more heated tothe usual coklng temperature of valuable constituents and bring aboutsecfrom 900 to 1000 C., the heat slowly peneondary reactions which yieldundesirable trates the fuel due to the low heat conducproducts. tivitlesof some of the layers of the fuel and The present invention relatesparticularly as a result the outside layer is heated to a very toby-product practice; that is to say, the high temperature before thecentral portion coking is done in a coking chamber and the of the massof fuel is heated sufficiently to gases and vapors are led away for theregive off its volatile matter. According to the 5 covery of theirvaluable constituents. It is present invention, the fuel is firstflooded.

the purpose of our invention to provide a with heat uniformlythroughout, that is, ex-

proeess and apparatus whereby fuel can be traneous heat is supplied tothe fuel in a coked so as to produce, even from poorly cokclosedcontainer so as to rapidly bring the ing coals a high grade product andeduce temperature of the fuel up to close to the crit- 4 the volatileconstituents without setting up ical temperature at which hydrocarbonvaundesirable secondary reactions. A further pors are educed. Thus allof the fuel is heatobject of our invention is to reduce the coned up toa temperature near the critical temsumption of fuel employed in theoperation perature in the most efficient manner. The and to makeavailable for use in by-product fuel so treated is brought into animproved 45 practice, coals of the character now commoncondition for thecarbonization process which is to follow, because of certain reactionsof an exothermic type which result in the removal ofdeleterious oxvgenand oxygen compounds such as H O and CO H These reactions if allowed tooccur simultaneously with the reactions of the carbonization stage wouldresult in a weakening of the bonding material and consequently produce acoke of inferior quality. It is to be understood that the reactionsinvolved in the process of carbonization occur at temperaturesimmediately following the pasty stage and are entirely different incharactor from those of the preliminary treatment stage. There is,therefore, the advantage that the preheating may be not only socontrolled as to bring themass up to within a few degrees of the pastystage where earbonization begins, but there is secured also a control ofthe chemical reactions involved whereby those of a deleterious characterare segregated from the carbonization reactions, thus producing astronger coke as well as discharging as undesirable material the CO andH 0 resulting from the preliminary heatlng.

When the fuel reaches the critical temperature, chemical reactions takeplace which generate a certain amount of heat. These exothermicreactions serve to change the chemical composition of the fuel in apronounced manner and to raise the temperature of the mass to aconsiderable extent. A characteristic of our invention is theutilization of this exothermic heat in raising the temperature of thefuel after the preliminary heat treatment. Because of the fact that thefuel is first heated uniformly throughout up to close to the criticalstage, the exothermic reactions augmented by the heat of the retortbring about the more pronounced exothermic reactions of decompositionand these occur throughout the Whole mass of coal. This rise intemperature produces more exothermic reactions and proceeds autogenouslyand with a cumulative effect so that not only does the pasty stagespread throughout the mass but the increased conductivity of the pastycondition promotes the transmission of heat from the retort walls andthis together with the heat resulting from the reactions quickly carriesthe carbonization process to completion. The autogenous progression ofthe exothermic reactions oftentimes has the effect of subjecting thefuel at the center of the mass to higher temperatures than thoseobtaining near the outer edge of the mass.

We prefer to supply extraneous heat to the fuel while the exothermicreactions are taking place for the purpose of avoiding heat loss byradiation, thus conserving the exo-' ing agitated, we have found that itis desirable to maintain the fuel in a quiescent con dition While theexothermic reactions are taking place and the plastic mass convertedinto co e.

Attempts have been made to convert coal into coke by tumbling it in arotating drum throughout the course of the entire process. This insuresuniform heating of the fuel up to the critical temperature but thismethod of treating the fuel does not produce coherout or concrete bodiesof coke. The tumbling of the fuel after it has become plastic isobviously not conducive to the production of a homogeneous product in aform which can be used without any such preliminary treatment asbriquetting. According to our invention, we propose to agitate the fuelduring the preliminary heating thereof and to maintain the fuelsubstantially quiescent while it is bein g changed from a plastic massto coke. The process thus consists of two main parts and the apparatuswhich We have devised for carrying out this process likewise comprisestwo fairly distinct devices which cooperate to produce the desiredresult.

Our apparatus includes a device whereby fuel such as coal can beuniformly heated throughout up to close to the critical temperature.,This means serves to heat the fuel in thin layers or while it is beinghandled so that the heat quickly and uniformly reaches every part of thefuel undergoing treatment, thus insuring a uniform temperature risethroughout the body of fuel. One embodiment of this portion of ourimproved apparatus comprises a cylinder into one end of which the coalis fed and in which a device is provided for simultaneously tumbling andadvancing the fuel. The cylinder is preferably arranged at a slightangle to the horizontal, the inclination serving to facilitate theadvancement of the fuel through the cylinder. Heat is supplied to thefuel preferably by heating the outside of the cylinder. The agitatingdevice may be in the form of a screw conveyor, which, upon beingrotated, will simultaneously-tumble the fuel in the cylinder and advanceit towards one end thereof. The cylinder may be heated by flue or otherwaste gases or a gas or oil burner may be installed in close proximityto the cylinder. We prefer to have the latter available for the reasonthat it makes it possible to control the heat in such a manner as tobring the mass to the exact temperature prescribed for theparticular'coal in hand.

The other principal part of the apparatus consists of a retort, orpreferably a group of retorts, into which the uniformly preheated fuelis deposited for the purpose of converting it into coke and dischargingthe hydrocarbon vapors which are educed as the temperature of the fuelincreases. This retort is conveniently located in close proximity to thepreheating device. We refer to provide a chamber between the rdl' eatingdevicehnd the retort proper for t e purpose of holding a reserve supplyof preheated fuel. This reserve chamber should hold' enough fuel to fillone retort completely and it shouldbe properly lagged to preventradiation losses. The fuel itself is naturally a poor conductor of heatand experience has shown that very little heat is lost throughradiation. Even if the fuel is permitted to stand for several hoursbefore being charged into the retort, the coke produced is of as highquality as that produced by charging the preheated fuel immediately intothe retort. The retort may be of the usual vertical type in which thecoal is introduced at the top and the coke is removed at the bottom.Means is provided for supplying heat to the outside of the retort forthe purpose of raising the temperature of the fuel up to the point wherethe exothermic reactions commence and to supply what additional heat isnecessary to conserve the exothermic heat and complete the cokingoperation.

Our process and the embodiment of our apparatus illustrated in theaccompanying drawings can best be understood after a consideration ofthe nature of the material treated and its behavior at differenttemperatures.

Bituminous coal (and likewise semi-bituminous coal) consists mainly oflignin or socalled degraded cellulosic material, and resinic orbituminic substances resulting from the geological transformation of thevege-' table matter in the formation of coal. The two main components ofall coals of the bituminous or semi-bituminous types may be separated byusing a suitable solvent such as phenol, and the characteristics of eachcomponent may be studied with reference to the role it plays in thecoking reactions. The lignin or insoluble part, consisting mainly oflignin, is one of the original components and also a resultant formed inthe degradation processes affecting the original plant cellu lose (C l-L0 In the transformations that have taken place, the greatest changeprobably has occurred with reference to the oxygen, which has droppedfrom a percentage of nearly 47 in the original cellulose, down to 12 or15% in the cellulosic residue. This residue has certain specificproperties of marked importance in connection with the coke formation.It does 'not melt or fuse together at any temperature and accordingly ithas no coking or bonding property whatever. It is fairly stable and doesnot decompose by the action of heat up to a temperature of 200 C. Abovethat temperature, and especially as 300 C. is approached, certaininitial decompositions begin, characterized mainly by a rearrangement ofthe elements of which the material is composed. Oxygen combines withhydrogen to form water and with carbon toform carbon dioxide and somecarbon monoxide. At higher temperatures, decomposition of a positivelydifferent type occurs which results 1n the formation of comounds ofcarbon and hydrogen, and of caron', hydrogen and ox gen. There is aresidue of carbon alone, w ich is neither coherent nor cakcd and cannotbe called coke.

The ccllulosic residue has a marked avidity for oxygen which it readilyabsorbs and retains even though heated to a fairly high temperature. Infact, as the temperature is increased, the oxygen enters into chemicalcombination before being discharged.

The bituminic or soluble component of the bituminousv or semi-bituminoustypes of coal is of a complex nature and includes substances directlyrelated to the resins. These 'resinic substances have undergone verylittle decomposition. This component also includes pitch-like compoundsin quantities predominating over the resinic substances; hence thedesignation bituminic substance.

The soluble or bituminic substance has a much smaller percentage ofoxygen and a greater percentage of hydrogen than the eellulosiccomponent of the fuel. The bituminic substance is like the cellulosicmaterial in that it resists decomposition at temperatures up to 200 6.,but unlike this material, it softens and-melts readily at temperaturesabove say 250 C. (the exact temperature depending upon the particularvariety of coal), and this without appreciable decomposition until aftera temperature of approximately 350 C. has been passed.

, When both the cellulosic and bituminous substances are heated abovethe melting point of the soluble material, the latter, in eilect atleast, has the property .of dissolving the cellulosic substance so thatif the heating process is continued, the entire coal mass will be of apasty or viscous consistency, and upon cooling from this point, willhave a vitreous appearance and glistening fracture, indicating that themass has become homogeneous throughout and has lost entirely thesegregated or laminated structure of the original coal.

For sometime it has been the generally accepted theory that the oxygencontent of a coal is largely or entirely the criterion for determiningwhether that particular coal is a coking or a non-coking coal, and thereis authority for the view that the ratio of oxygen to hydrogen availablefor combining therewith is the determining factor. Our investigationshave demonstrated that the coking quality, as we shall hereinafterdesignate the capacity for producing a. coke of high resistance tocrushing strain is dependent upon the possibility of removing the oxygenin the form of H 0 and CO or CO in a manner such as described under ourdiscussion of preheating up to approximately 300 C.

Another feature of our invention consists of an improved furnaceconstruction whereby heat can be supplied to the retorts in a .veryefiieient manner, the intensity of heat being substantially uniformthroughout the length of each retort. According to our invention the hotgases are used first to heat a refractory wall which in turnradiateslieat to the retorts. The gases are finally led into directcontact with the retorts and are finally discharged into the preheatingchamber of the preheating device.

The various objects and advantages of our invention can be bestunderstood by considering the accompanying drawings which show oneembodiment of an improved apparatus by means of which our improvedprocess can beperformed. In the accompanying drawings Figure 1 is avertical section View of-a coking apparatus made in accordance with our,invention.

Figure 2 is an end elevation of the apparatus shown in Figure 1.

Figure 3 is a vertical section'view of our improved flue construction.

Figure 4 is a transverse section view taken on line 4-4 of Figure 3showing the flue construction. I

Figure 5 is a vertical section View taken on line 55 of Figure 3 showingthe flue construction.

Figure 6 is a vertical section view taken on line 66 of Figure 3 showingthe flue construction.

The apparatus shown in the accompanying drawings comprises a battery ofthree vertical retorts 1, 2 and 3 and a preheating device 4communicating with the retorts through a reservoir 5. The retorts restupon foundation 6 and the preheating device is supported by columns 7.The retorts 1, 2 and 3 are supported on one floor 8 of the coking plantand the preheating device is supported on a level with the floor 9above.

The preheating device comprises a firebrick chamber 10 arranged for theutilization of waste heat from the fines surrounding the retorts 1. 2and 3. A pipe 11 supplies the flue gases to three distributing pipes 12.13 and 14 which open into the base of the preheating chamber 10 andserve to supply the hot gases uniformly along the cylinder 15 whichextends lengthwise throughout the chamber 10. A gas take-off 23 islocated in the top of the preheating chamber 10. A gas burner 16 havingan air injector 22 is arranged within the preheating chamber 10 near thebottom thereof. Both the chamber 10 and the cylinder 15 are inclined ata slight angle to the horizontal with the lower end adjacent to theupper ends of the retorts. A hopper 17, having a sliding valve 17therein, is located near the elevated end of the chamber 10 andcommunicates with the cylinder 15 by means of a pipe l8'whereby coal,preferably in finely ground form, can be introduced into the cylinder. Ascrew or worm 19 extends lengthwise through the cylinder 15 and theshaft of this screw is connected to a drive pulley 20. The screw 19 isdriven at a constant rate and serves to simultaneously tumble andadvance the coal in the cylinder 15 while the coal is being heated. Thecylinder 15 is large enough so that there'is a relatively large amountof free space in the cylinder as the coal is being advancedtherethrough. The worm 19 in the preheating cylinder 15 forces the fuelout of the end of the cylinder into the reservoir or storage hopper 5and the water vapors and gases driven off by the preliminary heating arecollected through a take-off pipe 21 near the top of the reservoir 5.The fuel in passing through the cylinder 15 is quickly heated uniformlythroughout up to close to the critical temperature, that is, up to'close to the temperature at which the particular grade of fuel employedbegins to soften. This critical temperature is fairly constant for anygiven grade of fuel and accordingly it is entirely feasible to adjustthe supply of extraneous heat so as to bring the fuel up to the desiredtemperature close to the criti* cal temperature. The burner 16,which'may be a gas burner or an oil burner, is of particular value evenwhere the waste flue gases from the retorts are used for the purpose ofheating the preheating cylinder 15. The burner 16, controlled by a valve22, is a convenient means for bringing the temperature in the cylinder15 up to exactly the desired point. This burner could of course be usedall by itself but it is more economical to utilize the heat in the wasteflue gases in heating up the raw fuel.

The fuel during the preliminary heating can be passed through thecylinder 15 at any desired rate depending upon the rate at whichextraneous heat is applied to the preheating chamber. If the heat issupplied at a rapid rate, a charge of say 100 pounds of finely groundcoal can be preheated uniformly throughout up to the desired temperaturein as short a time as 3 minutes. It is obw'ous that the method ofpreheating employed, that is, by agitating the fuel while applying heatthereto, is conducive to raising the temperature of the fuel Veryrapidly as compared with the rate at which fuel can be heated by placingit in a retort and simply applying heat to the outside of the retort,without agitating the fuel.

The fuel upon issuing from the lower end of the preheating cylinder 15flows into the reservoir 5 where it accumulates ready for charging intothe retorts 1, 2 and 3. The reservoir 5 is preferably made out of heatinsulating material so as to conserve the heat in the fuel which isdeposited in the reservoir. The fuel itself is a relatively poorconductor of heat and would not lose any considerable portion thereofeven if no precautions were taken with a view to preventing heat lossfrom the fuel. The fuel preheated in this manner can be held forsometime before charging into the vertical retorts and the quality ofthe coke produced is as good as that which would be produced by chargingthe preheated fuel into the retorts immediately after it issues from thepreheating cylinder. The preheated fuel can of course be fed directlyinto the retorts without letting it accumulate in the reservoir 5, if itis desired to operate the plant in this way. The reservoir 5 is providedwith 3 hoppers 24, 25 and 26 communicatin with the retorts 1, 2 and 3respectively. l alves 24", 25' and 26' control the supply of fuel to theretorts. These valves canbe regulated so as to control the rate of flowof the fuel and the flow can be entirely shut off when the retorts arefull.

We have found the apparatus just described to be of material valuebecause of the fact that it makes it possible to discharge the fuel intothe retorts at a predetermined rate. Prior to introducing the fuel intothe retorts, they are heated to a temperature in the neighborhood of 750C. and the fuel in dropping into the retorts becomes hotter as it flowsthrough the heated space. By regulating the valves 24', 25' and 26' tocause the fuel to flow at a relatively slow rate, the temperature of thefuel as it flows into the retorts increases considerably. The valves maybe regulated so that the temperature of the fuel will increase up to thecritical'value or even higher. Thus, by regulating-the rate at which thefuel flows into the retorts, the temperature at which the cokingoperation proper commences can be controlled.

Each of the vertical retorts comprises a metal cylinder approximately 12feet long and 14 inches in diameter, the diameter increasing graduallytoward the lower end of the retort. This. tapered construction has theadvantage of making it very easy to remove the coke from the retort. Wehave found, however, that a vertical retort with straight sides can beused because, even with this construction, it is not diflicult to removethe coke.

The retorts 1, 2 and 3 are preferably made out of one of the well knownheat resisting alloys, such as calorized iron or an alloy consisting ofapproximately 50% iron, 30% nickel and 20% chromium.

Gas and vapor take-ofl'. pipes 27 and 28 communicate with the upper endof each of the retorts 1, 2 and 3 and serve as a means for cooling thegas and vapors educed by the heat treatment of the fuel in the retorts.

The heating chamber surrounding the three retorts 1, 2 and 3 is ofspecial construclength of each retort. The heating chamber I comprisesan outer casing 29 of refractory material containing baffles 30. A as oroil burner 31 is installed in the base of the heating chamber, and inthe embodiment illustrated in the accompanying drawings this burner isprovided with 6 burner tips 32. Hot gases could of course be injectedinto the heating chamber instead of the flames from the burner tips, butthe burner disclosed in the drawin is particularly satisfactory becauseit candfe carefully adjusted to secure the desired temperature. Thebaffles 30 form channels in the wall 29 of the heating chamber and thearrangement is such that the portion of the wall between the bafiles andthe retorts is subjected to the action of the hot gases before the gasescome in contact with the retorts themselves. As shown in Fi ures burnertips 32 pass up in the channel 33 and down in the adjacent channel 34and then through an opening 35 at the base of this channel into' thespace 36 surrounding the retort 3. By referring to the drawings,partleularly Figure 4, it will be noted that each of the retorts l, 2and 3 is enclosed by a wall 37 which is heated by hot gases which comein contact with the outside of this wall. This hot wall radiates heat tothe retorts and serves to heat the retorts uniformly throughout theirlength. This action is sup lemented by the passage of the hot gases intoirect contact with the retorts after they have heated the outsides ofthe walls 37.

The character of the coke produced of course depends in a large measureon the heat treatment of the fuel in the retorts. Coke can be producedby simply dropping the preheated fuel into the retorts previously heatedup to approximately 750 0., without supplying additional heat to theretorts. Such coke, however, contains a fairly high percentage ofvolatile constituents, the ultimate temperature of the coke being nothigher than 500 to 600 C. By supplying additional extraneous heat to thefuel after it has been deposited in 3, 5 and 6, the hot gases from oneofthe the retorts, the percentage of volatile constituents in the cokeproduced can be reduced to any desired value; this heat treatment can beeven carried to the point where metallurgical coke is produced.

In Figure 2 we have shown in addition to the preheating device andretorts, a fuel bin 38 and a grinder 39 adapted to receive fuel from thebin through a spout 40. The ground fuel is lifted by means of a hoist41up to the level of the hopper 17 of the preheating apparatus.

The preliminaryheat treatment of the fuel in the preheating apparatusserves not only to increase the temperature of the fuel up to a certainvalue close to the critical temperature, but to condition the fuel bydriving out a fairly large percentage of the oxygen containedin thefuel. The oxygen is driven off in the form of water, CO and CO. Thispreliminary heating of the fuel serves to increase the h drogen-oxygenratio. If coal having a hy rogen to oxygen ratio of 0.6 to 1 or less(so-called non-coking coal) is subjected to this preliminary heattreatment, enough oxygen is driven out to bring the ratio up to a valuecomparable with that of coal considered to be in the coking class.

If the temperature of the preheated fuel is increased another incrementof 20 C. by supplying extraneous heat and utilizing the exothermic heatwhich is generated'within this range of temperatures, the fuel becomesplastic throughout and it is rapidly converted into coke. The entireprocess, including'preheating the fuel and converting it into coke inthe retorts, can be carried out in 2 or 3 hours.

It is to be understood that our apparatus can be varied withoutdeparting from the spirit of the invention which is not limited to theparticular embodiments illustrated and described, but includes suchmodifications thereof as fall within the scope of the appended claims.For example, while we prefer to use the type of preheating apparatusillustrated and described, yet it will be understood that other devicesby which coal can be uniformly heated throughout up to a tempera- I turebelow the critical temperature, preferably by simultaneously tumblingand advancing the fuel while heating the same, may be em loyed.

e claim: 1. In an apparatus for coking coal, an elonclose to thecritical tem erature, and a heat insulated storage cham er communicatingwith the retort and with the preheating means. 4. An apparatus forcoking coal, comprismg a coking retort, a heat insulated chambercommunicating directly with the retort, a valve for controlling the rateof flow of the fuel into the retort, a preheating drum communicatingwith the said chamber, means within the said drum for supplying fuel tothe chamber, and means for heating the said drum uniformly throughout,the said chamber having a capacity at least equal to that of the retort.

In testimony whereof we afiix our signatures.

SAMUEL W. PARR. THOMAS ERNEST LAYNG.

gated retort comprising a fuel container, an

inner refractory wall enclosing said container and spaced therefrom, asecond refractory wall enclosing said inner wall, bafiles between saidwalls forming channels for the passage of heating gases, and means forsupplying hot gases to said channels to heat said mner wall and therebyradiate heat to said container, said bafiles being constructed andarranged so that the hot gases may passthrough the channels from one endof the re- I tort to the other and back again outside of said inner walland then into direct contact with said container.

2. An apparatus for coking coal, comprising a coking retort, means forpreheating the fuel uniformly throughout, an enclosed heat insulatedreservoir communicating with the retort and arranged to receive fuelfrom the preheatin means, and means for controlling the rate 0% supplyof fuel to the retort.

3. An apparatus for coking coal comprising a coking retort, means forsupplying heat to all parts thereof uniformly, means for preheating thefuel uniformly throughout up to

